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Congenital goiter of the lamb
Congenital goiter is a swelling of the lamb's thyroid gland, visible at birth under the throat, at the base of the neck. The thyroid produces hormones that control growth, heat production and wool development. To make them, it needs iodine....
What is it?
Congenital goiter is a swelling of the lamb's thyroid gland, visible at birth under the throat, at the base of the neck.
The thyroid produces hormones that control growth, heat production and wool development. To make them, it needs iodine. If the ewe lacks iodine during its gestation, the lamb also lacks it: its thyroid works in a vacuum, grows to compensate, and forms this mass under the throat.
It is therefore not a disease of the lamb. It is an illness from the mother's diet, which occurs in the little one. Treating it in the lamb is almost useless; It is the feeding of the pregnant sheep that must be tackled, and for the following campaign.
Commonly observed signs
These signs are neither exhaustive nor specific. Only a veterinarian can establish a diagnosis.
Related signs — each one links to its page:
In lamb: swelling on each side of the throat, at the base of the neck, sometimes the size of a walnut, sometimes much larger. The mass is firm, symmetrical, not painful.
Lamb born dead or dying within the first hours despite an apparently normal gestation.
Weak lamb, unable to get up and suckle, which gets cold very quickly.
Wool absent or very sparse: the skin is bare in patches, especially on the head, neck and limbs, whereas a normal lamb is born well covered. This nudity largely explains cold mortality.
Difficulty breathing when the thyroid is very large and compresses the throat.
Surviving lambs that grow poorly, remain small and limp, and fall behind.
In sheep: nothing visible in general. Sometimes birthing difficulties, abortions late in gestation and an unusual proportion of stillborn lambs.
When to consult without delay
This list does not replace veterinary advice. It gathers situations that justify a prompt consultation.
Causes and risk factors
The central cause is a lack of iodine in the ewe's diet during gestation, particularly in the final months when the fetus develops most quickly.
Some regions have soils and forages naturally poor in iodine; areas far from the sea are typically the most affected.
Certain plants block the use of iodine even when it is present in the ration: this is the case for cabbages and cruciferous vegetables in general, as well as certain legumes and certain oilcakes distributed in quantity. A diet rich in these foods can cause a goiter even though iodine is not absent.
Excess nitrates or calcium in the water or diet can also interfere with the use of iodine.
Finally, mineral supplementation that is absent, expired, poorly distributed or inaccessible to part of the herd produces the same result as a total absence of iodine.
Areas and soils poor in iodine, fodder produced locally without mineral supplementation.
End of gestation ration based on cabbages, cruciferous vegetables, legumes or oilcakes in large quantities.
Absence of licking block or mineral supplement, or blocks in insufficient number for all the ewes to access them: the dominated ones never go there.
Mineral blocks exposed to rain, faded or old, whose real content is no longer assured.
Ewes carrying multiple lambs, whose needs are higher.
Water loaded with nitrates.
Herds managed extensively on range, without supplementation at the end of gestation.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
The diagnosis is first made at birth: the veterinarian palpates the lambs' throats and recognizes the enlarged thyroid.
He notes the elements that go together: stillborn lambs, naked lambs, early mortality, swelling of the neck. This association is very evocative.
Examining a dead lamb allows the thyroid to be weighed and directly observed, providing the strongest confirmation. It is therefore useful not to get rid of stillborn lambs before speaking to the veterinarian.
Analyzes can be carried out on ewes' blood or milk to assess the iodine status of the herd.
The veterinarian examines the end-of-gestation ration in detail: nature of the forage, presence of cruciferous vegetables, type and actual accessibility of the mineral supplement, quality of the water.
It rules out other causes of neck swelling in lambs, particularly abscesses, and other causes of neonatal mortality, including hypothermia and selenium deficiency.
Treatment
In a lamb already born with a goiter, the margin is narrow: the developmental damage is done.
The veterinarian can suggest an iodine supplement for the lamb, the form and method of administration of which fall under his prescription. Iodine is a narrow element: too much is toxic and causes its own problems. It should never be given in esteem or copied from a recommendation heard elsewhere.
Supportive care is essential and often decisive: immediately warm the lamb, dry it, protect it from wind and rain, ensure rapid intake of colostrum, feed it if necessary using a suitable method. A naked lamb dies of cold long before it dies of its goiter.
Lambs whose thyroid compresses the throat and who breathe poorly have a very unfavorable prognosis.
The real treatment actually takes place at the herd level and for the following campaign: correction of the iodine intake of pregnant ewes, under veterinary supervision. If ewes are still pregnant at the time of diagnosis, an immediate correction of their ration can save the unborn lambs: this is the most urgent measure to take.
Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.
Prevention
Ensure iodine intake for ewes throughout gestation, and particularly in the final months, with a mineral supplement suitable for sheep chosen with the veterinarian.
Be absolutely careful with supplements intended for other species: minerals intended for cattle often contain copper at levels dangerous for sheep, in whom it accumulates and causes fatal poisoning. Never transpose a product from one species to another without veterinary advice.
Check that the entire herd actually has access to the supplement: several distribution points, sheltered from the rain, renewed regularly. A single block per hundred sheep only feeds the dominant ones.
Limit the share of cabbages, cruciferous vegetables and cakes in the end-of-gestation ration, or compensate for their effect with the veterinarian.
Have forages and water tested when an area is known for poor soils.
Monitor lambs at birth: feel the throat and note naked or stillborn lambs, these are the first signals.
Talk to the veterinarian from the first abnormal campaign, without waiting for a second season of losses.
Possible complications
Significant mortality of lambs in the first hours and first days, especially from the cold.
Stillborn lambs and late gestation abortions.
Difficulties giving birth when the fetal thyroid is very large.
Surviving lambs with lasting growth retardation and poor quality wool.
Increased susceptibility to all other diseases of the newborn, the lamb being weak and poorly protected.
Catastrophic lambing results at flock level if the ration is not corrected for the following campaign.
When to see a veterinarian
Lambs are born with swelling on either side of the throat.
Several lambs are born dead or die in the first hours despite normal gestation.
Lambs are born naked or barely covered with wool.
A newborn lamb has difficulty breathing with an abnormally thick neck.
Newborn mortality is higher than usual this campaign: have the ration of pregnant ewes examined.
You have ewes still pregnant while the first lambs are showing these signs: it's a driving emergency, call the vet straight away.
Prognosis
For the lamb born with a large goiter, the prognosis is poor: many die within the first hours, especially if they are naked and exposed to the cold.
Little affected lambs, warmed up and well fed, can cope but often lag behind.
For the flock, the prognosis is excellent as soon as the ration of pregnant ewes is corrected: the following campaign can be normal. It is a disease that is cured by diet, not by caring for the sick.
Frequently asked questions
My lambs are born with a lump under their throat, is it an abscess?
An abscess is usually one-sided, warm and painful, and does not appear at birth. A symmetrical swelling on both sides of the throat in a newly born lamb primarily suggests a goiter linked to a lack of iodine in the mother. The veterinarian will make the difference.
Why are my sheep in great shape if they lack iodine?
Because the adult tolerates a moderate deficiency quite well, while the fetus has a critical need for it to develop. This is precisely what makes the disease sneaky: the flock appears impeccable until the day of lambing.
Can I give iodine to my sheep myself?
No, not by dead reckoning. Iodine has a narrow margin between necessary and toxic, and too much creates its own problems. The form, support and way of distributing it are decided with the veterinarian, who will take into account the ration and the region.
Can I use the mineral supplement from my cows for my sheep?
Especially not. Minerals formulated for cattle generally contain copper at levels dangerous to sheep, who accumulate it in the liver and can die from a poisoning attack. Only use a supplement intended for sheep and approved by your veterinarian.
References
FAO — Organisation des Nations unies pour l'alimentation et l'agriculture
Content reviewed by the TunisieVet editorial team · Updated 11 August 2026
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